Apparatus for extruding metals



June 30, 1936. c. c, JACQBSQN 2,045.655

APPARATUS FOR EXTRUDING METALS Fi led July so, 1932 I 2 Sheets-Sheet 1 INVENTOR June 1936- c; c. JACOBSON' APPARATUS FOR EXTRUDING METALS 2- Sheets-Sheet 2 Filed July 30, 1932 INVENTOR TTORN s Patented June 30, 1936 v UNITED. STATES PATENT OFFICE to John Robertson (30., Inc., Broo a corporation of New York klyn, N. Y

Application July 30, 1932, Serial No. 626,442 2 Claims. (01. 207-2),

. The present invention relates to an apparatus for extruding metals, and more particularly to the apparatus for melting lead and lead alloys, and filling the extruding cylinder of a lead cable press and the like with such molten metal free from oxides.

In the art of extruding lead, lead alloys and the like, the presence of oxides of lead in the melting pot and in the extrusion cylinder have 16 always proven objectionable, and when such oxides are trapped into the lead which sheathes a cable it is a known fact that they cause weakness in said sheath which materially impairs the usefulness of the cable. Care is accordingly exercised and various means have been devised in seeking to reduce to a minimum the formation of subh objectionable oxides during the melting and extruding of lead.

According to the present invention I accomplish these ends through the employment of a novel kettle or chamber in which the lead ismelted in an atmosphere of an inert or non-oxidizing gas and the provision of means for introducing such gas into the lead delivery tube around the draw-off valve and into the extrusion cylincler of the press, so that when said cylinder is being filled with lead preparatory to extruding the, metal, said metal will flow through this inert or non-oxidizing'gas charged space out of con- 3 tact with the air and thereby practically'elim inate and reduce to a minimum the formation of the objectionable oxides. The means which I employ and the method which I follow will be .fully understood from the 'detailed description which, follows, when considered-in conjunction with the, accompanying drawings which show a preferredg embodiment of my invention, and wherein a Figure Us a side elevation of a lead cable press 1 and lead melting kettle, parts thereof .being shown in section to better illustrate the cons'truction thereof.

Fig. 2 is a section taken substantially along the planes of the broken line 2-2 of Fig. 1. o

i 1 Fig. ,3is a section taken substantially along the plane of the broken lined-3 of Fig. 1, showing the position of the delivery chute when the extrusion cylinder is ready to receive the ram.

Fig. 4 is an enlarged view of the drawoli valve, 9 delivery tube and associated parts.

-- vable-lwithin an extrusion cylinder a to sheathe lead cable which is drawn through a die-block a, the type of cable press and its manner of operation being well known are not here described in detail. I 1

Mounted in close, proximity to the cable press 5 1 A is a lead melting pot or kettle .B suitably mounted above a fire-box C within a housing D lined with fire-brick d and heat insulating brick d, there being a firing hole D inthe lower portion of said wall. g

The melting pot or kettle B is preferably constructed of welded steel plates and is equipped with a draw-off spout b which extends through the wall of the kettle somewhat. above the bottom thereof and is of a length to extendinwardl5 ly into the kettle to a point near the center thereof so that in drawing oh the melted lead from the kettle, said molten metal will be drawn from approximately the center of the melting pot, and the possibility of drawing oil dress or 20 foreign matter which may have accumulated on the sides of the melting pot will thereby be avoided or reduced to a minimum. The draw-off spout b is preferably welded into the wall of the melting potand extends outwardly therefrom to a 25 point within the enclosing wall vD provided with an opening d through which extends the end of a delivery tube E having an offset spout e extending outwardly and downwardly through the wall D. The draw-off tube b is secured to 30 the delivery tube E by screw-threads or other equivalent means. Suitably supported by the delivery tube E is the draw-off control valve F whichis mounted at one end of a valve stem I which screw-threadedly engages within a bush- '35 ing f and slidably passes through a packed joint f, the bushing f and pacmng gland I being suitably carried by the delivery tube E. At the outer end of the valve stem] is a hand wheel F for manipulating the valve. Disposed on the out- 40 er side of the wall D around the opening :1 and enclosing the delivery tube E and draw-off valve F is a guard plate G which serves toprotect an operator from the heat and flame within the firebox and which. extends up' around the kettle B, 46 the draw-off spout b, the delivery tube E and draw-off valve F. x

The kettle B extends upwardly beyond the top of-the enclosing wall D, upon which it is suitably. supported in any approved manner, such, for ex- 50 ample, by having an encircling channel member b which is welded thereto, seating upon an annular flange it upona wall-capring d. A suit-' ably insulated closure or cover member H is provided for the kettle B, which cover member has a vent opening through which extends a valve tube It fitted with a relief valve h, a gas inlet opening through which extends the pipe 72., an inspection opening it suitably protected with a glass cover, and openings h in which electric illuminating means can be disposed so that the interior of the kettle above the surface of the molten lead might be illuminated for inspection through the opening h. Also extending through the cover H and terminating in spaced relation to the bottom of the kettle B is a cylindrical metal tube J, the bottom of which is provided with a grate 1', which tube serves as a, melting chamber for the lead. The purpose of this melting chamber is to receive the pigs of new lead which are delivered to this melting chamber on a roller conveyor K past a chain guard Icarried by a charging hood L which is mounted directly over the melting chamber J. The lead in this melting chamber melts at the lowest possible temperature, and because the lead at the top of this melting chamber is only slightly above the melting point of lead, very little dross or oxides are formed, and these are easily skimmed off and are thereby prevented from going down through the grate 7 into the melting kettle B. The grate :i also prevents the pigs of new lead from passing through the melting chamber J in unmelted condition into the kettle B.

To prevent the formation of lead oxides within the kettle B, provision is made for introducing and-maintaining in the kettle above the surface of the molten metal an inert or non-oxidizing atmosphere, such as carbon dioxide. The carbon dioxide or other non-oxidizing gas may be supplied to the kettle from 'a commercial tank of such gas M through the conducting pipe m and minto an expansion tank N, and then through the pipe h into kettle B. The expansion tank N is designed to keep a constant supply of the gas in the melting pot above the molten metal, and sufficient pressure is maintained in the tank N so that as the level of the molten metal recedes, the

. inert gas fiows into the melting pot, and as the metal level rises, the inert gas is forced back into the tank N. The relief valve 72. may be used to relieve the gas pressure in the kettle and tank N should the same become excessive. To prevent the escape of gas from the kettle B or any entrance of air thereinto, all the joints are sealed either by welding, by asbestos gaskets, or other means known to engineering science. To also it is necessary to preserve the metal in this condition until after it is introduced into the extrusion cylinder a. To accomplish this I have provided means whereby the molten metal, as it is being withdrawn from the melting pot and conveyed to the extrusion cylinder, will be surrounded or will move in an atmosphere of inert gas, and to further insure against this metal becoming oxidized.

upon reaching the extrusion cylinder I have provided means for charging said cylinder with the inert gas which is displaced as the metal flows.

into said cylinder. I will now describe the means whereby I accomplish this.

The supply of inert gas for this purpose is obtained from the tank M through the tube m. through control valve 0' into expansion tank 0 wherein sufilcient pressure is maintained to provide for a charge of gas for the lead cylinder when it is required. The gas to be supplied to the lead cylinder and for providing the inert gas atmosphere around the molten lead while it is being charged into said cylinder is preferably preheated so as to avoid loss of temperature and too rapid cooling of the molten metal as it is being introduced into the cylinder. This preheating isaccomplished by passing the gas through a heating coil P which is located in the lining of the encircling wall D of the melting furnace. The discharge end of this heating coil is connected by a pipe 17, a valve p and a discharge tube 12 to an annular groove p in the delivery tube E and connecting with the ofi'set portion-e thereof,

' the draw-off tube 12, the delivery tube E, the

draw-off valve F, the gas supply-means O, P, p and p", and the delivery chute B, it will be apparent that I have provided means for selectively charging the lead cylinder with molten metal, with the gas, or with both the metal and the gas simultaneously, as desired. And as it is necessary in the operation of the device to resort to these selective controls, 'I will now describe the cycle of operations that is followed in the operation of the present invention. The kettle B being filled with molten lead to its normal level indicated by the dotted line a: (Fig. 1) and there being an atmosphere of inert gas above the surface of the metal in said kettle, gas is admitted through control valve 0' into the expansion tank 0 until a predetermined pressure is indicated .therein by the gauge 0 attached thereto. During this time the valve p is kept closed. At the end of the extrusion cycle when the extrusion ram a and the extrusion lead cylinder a are in their positions, as indicated in Fig. 1, the delivery chute R is moved into the position shown and the valve 10' is opened. This admits the hot carbon dioxide to the lead delivery tube E and thence down through the delivery chute R to the extrusion cylinder 11' under suflicient pressure and in suflicient quantity to displace all the free air or oxygen from said cylinder. The lead draw-off valve F is then'opened by rotating the hand wheel I which moves .the valve plug F away from its seat in the draw-oil tube b, thereby admitting lead from substantially the center of the melting pot B to the delivery tube E, de-

livery chute R and extrusion cylinder 0'. These latter three. parts having been previously filled with carbon dioxide, the lead does not come in contact with the free air or oxygen, and accordingly no oxides can be formed. When the extrusion cylinder a has been filled, the delivery chute R is moved to one side as shown in Fig. 3 and the extrusion-started. Valve 1) is now closed and valve 0' opened, thereby admitting a new charge of carbon dioxide to the expansion tank 0 and .coil P to be preheated and made ready for the next filling operation of the extrusion cylinder.

From the foregoing detailed description it will 75 2,045,655 beapparent that I have disclosed a mechanism and method particularly adapted for the purpose of supplying molten lead free from oxides to the extrusion cylinder of a cable press, and although the present device is primarily directed to this particular use, it is to be understood that the invention is capable and susceptible of miscellaneous uses where oxide-free molten metals are Accordingly I ited to the particular use to which I have herein made reference, nor to the specific details of construction for the various parts as disclosed, since the same maybe varied within the range of; engineering skill without departing from the spirit of -myjinvention.

What I claim ist 1. In combination, an extrusion press cylinder,

a melting kettle. a source of non-oxidizing gas,

means {or selectively charging said cylinder with molten metal, gas, or both metal and-gassimultaneously, said means comprising a delivery chute having connection with both the melting kettle and the source of gas, and means surrounding the melting kettle and adapted to derive heat therefrom for preheating the gas.

2. In combination, an extrusion press cylinder a melting kettle, a source of non-oxidizing gas, means for selectively charging said cylinder with molten metahgas, 'or both the metal and gas simultaneously, said means comprising a delivery chute having connection with both the melting kettle and the source of gas, and independently operable valves in the connecting means leading from the melting kettle and from the gas source respectively, the valve which controls the flow of molten metal from the melting kettle to the de-,

livery chute being outside the-melting kettle and CONRAD c. JACOBSOlI. 

